In a lead frame with the bar lead (it is also called a bus bar) which is a common lead used for stabilization of a power source/GND etc., when arranging the bar lead of ring shape, it is arranged in the region surrounded by the inner lead tip group of each side. In that case, each inner lead tip is stuck on the sheet member via the insulation member, further, a chip mounting region is formed in the about central part of the sheet member, and the bar lead of ring shape is arranged in the region between the chip mounting region and the tip group of inner leads.
If it is going to form a plurality of bar leads of ring shape for reinforcement of a power source/GND, the combination part of each bar lead will increase, therefore a cutting part will also increase. About the various lead frames in which a plurality of bar leads of ring shape were formed, PCT/JP03/06151 have the description.
When a bar lead increases, since not only connection of a bar lead but a lead pattern becomes complicated, rigidity must be increased also as the whole lead frame and reinforcement of a lead frame is needed. In order to maintain the strength of a frame, a connection part must be increased, and as a result cutting parts will also increase in number and consideration is needed also about how at the time of cutting to put in a punch, or abrasion of a punch.
Although Japanese Unexamined Patent Publication No. Hei 9-252072 has the description about the lead frame of the structure where the tips of a plurality of leads are connected, the analyses about the reinforcement of a lead at the time of increasing a bar lead or the punch at the time of cutting are not made.
The purpose of the present invention is to offer a manufacturing method of a lead frame which increases rigidity.
The other purpose of the present invention is to offer a manufacturing method of a lead frame which aims at elongation of lifetime of the punch for cutting.
The above-described and the other purposes and novel features of the present invention will become apparent from the description herein and accompanying drawings.